For the IRA LLC it's a special purpose LLC that's created to be designed by the IRA. 

Here are the details:Assumable loan balance: $750k at 2.75%List price: $950kDownpayment needed: $200k to cover the differenceMy initial plan to make this deal work included a few options:Getting a loan for the $200k difference.Bringing in a partner.Asking for seller financing.However, when I discussed these options with my agent, I hit a few roadblocks:Second Mortgage: My agent said no bank would provide a second position loan for the $200k.Seller Financing: He mentioned that 99% of sellers would reject this, though we're asking anyway.Agent's Advice: He suggested I just get a conventional loan and put 5% down for the full $950k, but I feel this defeats the purpose of leveraging the assumable loan.Given these challenges, I’m trying to figure out the best way to raise the $200k.

If I was in your shoes I would gently let that person know what you plan on doing with the place and how much you're going to be charging etc...

Its a personal decision for sure.

Personal preference though 

This answer all depends on personal preference and budget.

I personally have used a heloc to purchase and renovate an investment property, like you mentioned I cashed out at the end and paid back the heloc. 

The main purpose is to separate your business from your personal so that if the business is ever sued they cannot come after your personal assets, but if you don't operate it as a business the LLC does not protect you. 

I have had attorneys easily show me how to pierce corporate vail by transferring to an LLC without it being arms length transaction especially if you personally are on the loan.

If you're looking for a long term business associate, in my personal opinion it is best to team up with someone that you want to make rich.